1. Field of the Invention
This invention is directed toward a new dehumidifier and a method for operating the dehumidifier.
The invention is more particularly directed toward a dehumidifier with novel means for use in defrosting the dehumidifier and a novel method for defrosting the dehumidifier.
2. Description of the Related Art Including Information Disclosed Under CFR .sctn..sctn. 1.97-1.99
Known dehumidifiers have a conditioning area in an air duct. An air mover, such as a fan, in the air duct draws air from a room through the conditioning area to dehumidify it. The conditioning area has an evaporator for cooling a portion of the air passing through the duct to cause moisture to condense from the air onto the evaporator to control its humidity. The moisture is collected from the evaporator in a drain pan located under the evaporator. The conditioning area also has a condenser for heating the remainder of the air passing through the duct. This heated air portion is mixed with the dehumidified air portion so that the air returned to the room is at a slightly higher temperature than the temperature at which it left the room but less humid.
A compressor circulates refrigerant through the conditioning area during dehumidification. The refrigerant leaves the compressor as a hot gas and at high pressure and normally passes through the condenser heating the portion of air passing over the condenser. The refrigerant is condensed to a liquid state in passing through the condenser. The liquid refrigerant then passes through a restrictor where it expands and lowers in temperature. From the restrictor, the refrigerant enters the evaporator as a mixture of gas and liquid at low pressure and temperature where it cools the portion of air passing over the evaporator. The refrigerant is returned to the compressor to repeat the cycle.
As the dehumidifier operates, ice can build up on the evaporator. The ice build up lowers the efficiency of the evaporator in cooling the air and restricts air flow. The dehumidifier must therefore be periodically defrosted so that it continues to operate efficiently.
Dehumidifiers are normally defrosted by reversing the flow of refrigerant from the compressor and shutting down the fan in the air duct. The hot refrigerant gas now flows first through the evaporator, melting the ice that has accumulated on it. The cooled refrigerant from the evaporator returns to the compressor through the condenser. Shutting down the air mover prevents the air from picking up moisture from the melting ice on the evaporator and being returned to the room. However, without airflow over the evaporator, defrosting takes quite a while. In addition, part of the cooled refrigerant can liquefy during defrosting and be returned to the compressor as a "slug" of liquid causing damage to the compressor. To minimize the formation of these liquid "slugs", and thus minimize damage to the compressor, defrosting is performed more frequently. This of course lengthens the time that the dehumidifier is not dehumidifying, reducing its efficiency and operating time span.